Spanish police said Thursday they have broken up a criminal group that exploited undocumented migrant workers in the agricultural sector, mainly from Morocco, and sold them false documents.

Officers arrested 43 people in the southern province of Malaga suspected of belonging to the ring, which charged illegal migrants up to 3,000 euros ($3,200) for fake work contracts to allow them to regularise their status, police said in a statement.

"Some of the migrants were housed in inhumane conditions in houses belonging to the organisation," it added.

A video released by police showed a cramped room with decrepit walls and a small single bed that was used to house migrants.

At least seven agricultural firms are believed to have taken part in the scheme dedicated to the "labour exploitation" of Moroccan nationals, the statement added.

Spain is a key gateway into Europe for illegal migration from Africa although arrival numbers decreased last year.

A total of 31,219 people entered Spain without permission last year, mainly by boat from Morocco -- a drop of 25.6 percent over 2021, according to interior ministry figures.

About 800,000 Moroccans legally live in Spain, making it the biggest foreign population in the country, according to national statistics institute INE figures.

Migrant workers face a higher risk of forced labour than other workers, according to the UN International Labour Organization (ILO).

"The forced labour prevalence of adult migrant workers is more than three times higher than that of adult non-migrant workers," it wrote in a September 2022 report.